scar vs cheloid

scar and cheloid both are nouns.

Word	Noun	Adjective	Verb	Adverb
scar	Yes	No	Yes	No
cheloid	Yes	No	No	No

As nouns, cheloid is a hyponym of scar; that is, cheloid is a word with a more specific, narrower meaning than scar:

scar: a mark left (usually on the skin) by the healing of injured tissue
cheloid: raised pinkish scar tissue at the site of an injury; results from excessive tissue repair

Other hyponyms of scar include callus, keloid, pockmark, sword-cut, vaccination.

scar (noun)	cheloid (noun)
an indication of damage	raised pinkish scar tissue at the site of an injury; results from excessive tissue repair
a mark left (usually on the skin) by the healing of injured tissue

scar (verb)	cheloid (verb)
mark with a scar